Conventionally, molded articles obtained by injection molding have been widely used for automobile interiors, domestic electric appliance exteriors and the like. In order to decorate such molded articles, for example, a technique named as a simultaneous injection molding and lamination method has been employed. The simultaneous injection molding and lamination method includes a method comprising the steps of inserting a decorated resin film between a male and a female dies for injection molding and injecting a melting resin from one side of the dies so as to form an injection molded article and paste the resin film simultaneously onto the molded article; a method comprising the steps of preliminarily molding a decorated resin film or a laminate film having the decorated film on one surface of another film by vacuum molding and then inserting the preliminarily molded film into an injection molding die, or preliminarily molding a decorated resin film or a laminate film having the decorated film in one surface of another film by vacuum molding, compressed air molding or the like in an injection molding die, and then injecting a melting resin to the die so as to integrally mold the preliminarily molded film with the resin. The latter method, that is, a method comprising the steps of preliminarily molding a film or a laminate film and then injecting a melting resin onto one surface of the film, is also called an insert molding method. Such a simultaneous injection molding and lamination methods are described in, for example, Japanese Patent Application Publication (JP-B) No. 63-6339, JP-B No. 4-9647, Japanese Patent Application Laid-Open (JP-A) No.7-9484 and the like.
An acrylic resin film is preferably employed for such simultaneous injection molding and lamination methods since the film is excellent in weathering resistance, good surface luster, surface hardness and surface smoothness.
In the simultaneous injection molding and lamination method, a resin film to be a surface layer is generally subjected to heating at 100° C. or higher. When a conventional acrylic resin film is used for the surface layer in this method, there is problems such that the roughness of the film surface is increased by such heating and the resulting film tends to have white turbidity to deteriorate design properties of the film. It has been, therefore, needed to solve the problem.